Non-invasive blood component analyzer
First Claim
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1. A non-invasive method for measuring the concentration of a blood component in a subject'"'"'s blood, said method comprising the steps of:
- (a) providing at least one light source for directing light of at least one wavelength through a tissue of the subject in which light absorbance of arterial blood can be detected by measuring changes in absorbance during pulsatile flow of blood,(b) providing at least one detector for detecting the portion of the light not absorbed by the tissue of the subject;
(c) measuring the absorbance of the light at the wavelength by the tissue at both the systolic and diastolic phase of the pulsatile flow;
(d) determining the physical dimension of said tissue at both the systolic and diastolic phase of the pulsatile flow;
(e) calculating a ratio of the change in light absorbance between the systolic and diastolic phase divided by the change in the physical dimension of said tissue between the systolic and diastolic phase;
(f) determining the concentration of the blood component by comparing the ratio calculated in step (e) to a reference.
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Abstract
A non-invasive blood component analyzer using spectrophotometry, with systole/diastole corrections for tissue absorbance, and with built-in monitoring of light path length to allow its accurate use in subjects with widely varying finger size and/or varying pulse amplitude. Blood components that are able to be analyzed include oxy-hemoglobin, total hemoglobin, bilirubin, glucose, hormone levels and a variety of drugs.
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Citations
50 Claims
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1. A non-invasive method for measuring the concentration of a blood component in a subject'"'"'s blood, said method comprising the steps of:
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(a) providing at least one light source for directing light of at least one wavelength through a tissue of the subject in which light absorbance of arterial blood can be detected by measuring changes in absorbance during pulsatile flow of blood, (b) providing at least one detector for detecting the portion of the light not absorbed by the tissue of the subject; (c) measuring the absorbance of the light at the wavelength by the tissue at both the systolic and diastolic phase of the pulsatile flow; (d) determining the physical dimension of said tissue at both the systolic and diastolic phase of the pulsatile flow; (e) calculating a ratio of the change in light absorbance between the systolic and diastolic phase divided by the change in the physical dimension of said tissue between the systolic and diastolic phase; (f) determining the concentration of the blood component by comparing the ratio calculated in step (e) to a reference. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A non-invasive method for measuring the concentration of a blood component in a subject'"'"'s blood, said method comprising the steps of:
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(a) choosing a first wavelength of light at which the blood component absorbs light relatively strongly and all other substances expected to be present in the subject'"'"'s blood absorb light to a lesser degree; (b) choosing a second wavelength of light to be used as a reference wavelength, said reference wavelength absorbed at a relatively low level by both the blood component of inte(rest and all other substances expected to be present in the subject'"'"'s blood; (c) providing a first light source for directing light at the first wavelength through a tissue of the subject in which light absorbance of arterial blood can be detected by measuring changes in absorbance during pulsatile flow of blood; (d) providing a second light source for directing light at the reference wavelength through the tissue of the subject, the second light source either being the first light source adapted to emit light at more than one wavelength or a separate light source located adjacent to the first light source; (e) providing at least one detector for detecting the portion of the light of the first wavelength and the light of the reference wavelength not absorbed by the tissue of the subject; (f) determining a physical dimension of the tissue at both the systolic and diastolic phases of the subject'"'"'s pulsatile flow; (g) calculating the change in the physical dimension of said tissue between the systolic and diastolic phases of the subject'"'"'s pulsatile flow; (h) measuring the absorbance of light at the first wavelength and the reference wavelength at the systolic and diastolic phases of pulsatile blood flow; (i) calculating the change in light absorbance between the systolic and diastolic phases for both the first wavelength and reference wavelength; (j) calculating the difference between the changes in absorbances at each of the two wavelengths calculated in step (i); (k) calculating a value by applying a formula dividing the difference between the changes in absorbances at the two wavelengths as calculated in step (i) by the change in the physical dimension of said tissue between the systolic and diastolic phases as calculated in step (g); (l) determining the concentration of the blood component by comparing the value calculated n step (k) to a reference. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A non-invasive method for measuring the concentration of a blood component in a subject'"'"'s blood by light absorbance when an interfering substance absorbs at the optimal wavelength for detecting the concentration of the blood component, said method comprising:
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(a) choosing three wavelengths of light, a first wavelength at which both the blood components and the interfering substance absorb relatively strongly in comparison to all other substances expected to be present in the subject'"'"'s blood, a second wavelength at which the blood component and the interfering substance absorb differentially, and a third wavelength at which the blood component and the interfering substance absorb at approximately the same low level; (b) providing a first light source for directing light at the first wavelength through a tissue of the subject in which light absorbance of arterial blood can be detected by measuring changes in absorbance during pulsatile flow of blood; (c) providing a second light source for directing light at the second wavelength through said tissue of the subject, the second light source either being the first light source adapted to emit light at more than one wavelength or a separate light source located adjacent the first light source, (d) providing a third light source for directing light at the third wavelength through the tissue or the subject, the third light source being either the first or second light sources adapted to emit light at more than one wavelength or a separate light source located adjacent the first and second light sources; (e) providing at least one detector for detecting the portion of the light of the first, second and third wavelengths not absorbed by the tissue of the subject; (f) measuring the absorbance of light at each of the three wavelengths at the systolic and diastolic phase of pulsatile blood flow; (g) calculating the change in light absorbance between the systolic and diastolic phases for each of the first, second, and third wavelengths; (h) calculating the difference between the changes in absorbances between the systolic and diastolic phases between the first and second wavelengths; (i) determining a physical dimension of said tissue at both the systolic and diastolic phases of the subject'"'"'s pulsatile flow; (j) calculating the change in the physical dimension of said tissue between the systolic and diastolic phases of the subject'"'"'s pulsatile flow; (k) calculating a value by applying a formula employing three empirically derived regression constants and three variables, the first variable being the ratio of the difference between the changes in absorbances between the systolic and diastolic phases at the first two wavelengths as calculated in step (h) to the change in the physical dimension of said tissue between the systolic and diastolic phases as calculated in step (j), the second variable being the ratio of the change in light absorbance between the diastolic and systolic phases for the third wavelength as calculated in step (g) to the change in the physical dimension of said tissue as calculated in step (j), and the third variable being the reciprocal of the change in the physical dimension of said tissue as calculated in step (j); (l) determining the concentration of said blood component by comparing the value calculated in step (k) to a reference. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. A non-invasive method for measuring the concentration of a blood component in a subject'"'"'s blood when an interfering substance absorbs at the optimal wavelength for detecting the concentration of the blood component, said method comprising:
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(a) choosing a first wavelength of light at which the blood component absorbs light relatively strongly in comparison to all other substances expected to be present in the subject'"'"'s blood and the interfering substance also absorbs light to a substantial degree; (b) choosing a second wavelength of light at which the interfering substance absorbs light to a substantial degree; (c) providing a first light source for directing light at the first wavelength through tissue of the subject in which the light absorbance of arterial blood can be detected by measuring changes in absorbance during pulsatile flow of blood; (d) providing a second light source for directing light at the second wavelength through the tissue of the subject, the second light source either being the first light source adapted to emit light at more than one wavelength or a separate light source located adjacent to the first light source; (e) providing at least one detector for detecting the portion of the light of the first wavelength and the second wavelength not absorbed by the tissue of the subject; (f) determining a physical dimension of said tissue at both the systolic and diastolic phases of the subject'"'"'s pulsatile flow; (g) calculating the change in the physical dimension of said tissue between the systolic and diastolic phases of the subject'"'"'s pulsatile flow; (h) measuring the absorbance of light for each of the first wavelength and the second wavelength at the systolic and diastolic phases of pulsatile blood flow; (i) calculating the change in light absorbance between the systolic and diastolic phases for both the first wavelength and second wavelengths; (j) calculating a ratio of the change in light absorbance as calculated in step (i) to the change in the physical dimension of said tissue and the detector as calculated in step (g) for each of the first and second wavelengths; (k) calculating a value by applying a formula employing three empirically derived regression constants and three variables, the first variable being the ratio of the change in light absorbance at the first wavelength to the change in the physical dimension of the tissue between the systolic and diastolic phases as determined in step (j), the second variable being the ratio of the change in light absorbance at the second wavelength to the change in the physical dimension of said tissue between systolic and diastolic phases as determined in step (j) and the third variable being the reciprocal of the change in the physical dimension of said tissue between the systolic and diastolic phases as calculated in step (g); and (l) determining the concentration of the blood component by comparing the value calculated in step (k) to a reference. - View Dependent Claims (38, 39, 40, 41, 42, 43, 44)
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45. A device for the non-invasive measurement of the concentration of a blood component in a subject'"'"'s blood, said device comprising:
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(a) at least one light transmission set comprising; (i) at least one light source; (ii) at least one detector for detecting the light emitted by the light source mounted apart from the light source such that the subject'"'"'s tissue is adapted to be interposed between the detector and light source, the light source mounted so as to transilluminate the tissue and the detector mounted so as to detect the light from said light source not absorbed by said tissue, (b) a base adapted for holding a portion of the tissue of the subject through which pulsatile flow of arterial blood can be detected, said base including at least a portion of the light transmission set; (c) means for measuring changes in a physical dimension of said tissue between the light source and the detector; (d) means for transmitting data from the light detector; (e) means for transmitting data from the means for measuring change in said physical dimension of said tissue; and (f) means for receiving the transmitted data and for calculating the concentration of the blood component by calculating the ratio of change in light absorbance in the systolic and diastolic phase divided by the change in physical dimension of the tissue and comparing the ratio to a reference. - View Dependent Claims (46, 47, 48, 49, 50)
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Specification